In the long search for effective medicaments to alleviate pain of different types, no other group of drugs have dominated the field more than the salicylates, which by virtue of their analgesic, antipyretic and antirheumatoid properties have been the drug of choice. The salicylates have many modes of action, some of which are not well understood, but they all have selective depressent effect on the central nervous system. While salicylic acid is very irritating and can be used only externally, the esters produced by the substitution of the hydroxyl group are extremely useful in oral therapy, such as acetylsalicylic acid or aspirin. When the carboxyl group is substituted, as in sodium salicylate or methylsalicylate, the irritant effect in the compound is still present.
In a recent U.S. Patent application (Ser. No. 841,734) the petitioners presented a novel chemical derivative of acetylsalicylic acid or aspirin, by the production synthetically N-N'dibenzylethylenediamine-diacetylsalicylate or DBED-aspirin which had lesser toxicity than aspirin or salicylamide (LD-50 by oral route in mice for DBED-aspirin is 3.5 grams/kg as against 1.75 grams/kg for aspirin and 1.4 grams/kg for salicylamide). It was also briefly mentioned that the DBED-aspirin when applied externally as an ointment was subcutaneously absorbed and brought about immediate pain relief. This obviated the oral administration salicylates. It further had the advantage of being used as a combined fortified therapy along with other pain killing agents.
Though considered safe, acetylsalicylic acid has its own adverse effects in some patients. Epigastric disturbances as vomitting, nausea often accompany oral treatment. Other forms of salicylate poisoning are well documented in medical literature. It is in this context that DBED-aspirin, a safe, non-irritant and highly potent analgesic substance is presented, which by its property of subcutaneous absorption when applied externally on skin, has a unique place in treatment of pain.
DBED-salts of penicillin, such as benzathine penicillin are used as injectables and by their depot action they give long sustained blood levels. The DBED-penicillin slowly breaks up into DBED molecule and penicillin. Thus it is seen that DBED molecule in blood stream is fairly non-toxic and well tolerated. However, the finding that in combination with acetylsalicylic acid and DBED molecule, a subcutaneously absorbed chemotherapeutant is produced, is a novel finding in the present invention.